The typical application fields of a photoresist are the manufacturing of a circuit substrate such as IC, and other photofabrication steps. The photoresist is coated on a substrate such as a semiconductor wafer, glass, ceramics, ITO, and metal by a spin coating method or a roller coating in a thickness of 0.3 to 3 .mu.m and then the coated substrate is heated for drying and a circuit pattern is printed thereon via an exposure mask by irradiation of UV rays, followed by developing, whereby a negative or positive image can be obtained. Further, etching is carried out using this image as a mask to provide a substrate with patternwise processing.
There is generally used as a positive type photoresist composition, a composition containing an alkali soluble resin and a naphthoquinonediazide compound as a light-sensitive substance. For example, there are described a novolak type phenol resin/a naphthoquinonediazide-substituted compound in U.S. Pat. Nos. 3,666,473, 4,115,128 and 4,173,470, and the example of a novolak resin consisting of cresol-formaldehyde/trihydroxybenzophenone-1,2-naphthoquinonediazide sulfonic acid ester as the most typical composition in "Introduction to Microlithography" written by L. F. Thompson (ACS Publication, No. 219, pp. 112 to 121).
In such a positive type photoresist fundamentally consisting of a novolak resin and a quinonediazide compound, the novolak resin can be dissolved in an alkaline aqueous solution without swelling and the naphthoquinonediazide compound acts as an anti-dissolution agent. Characteristically, naphthoquinonediazide loses its anti-dissolution capability and alkali solubility of the novolak resin increases when naphthoquinonediazide is subjected to light irradiation to generate carboxylic acid.
From this view-point, many of the positive type photoresists containing the novolak resin and naphthoquinonediazide type light-sensitive material have so far been developed and put into practical use, and sufficient results have been obtained in line width processing of not much more than 0.8 to 2 .mu.m.
Meanwhile, a composition containing an alkali soluble resin and an azide compound as a light-sensitive material is used as a negative type photoresist composition. There are published "a phenol resin/azide compound" resist in A series of azide-phenolic resin resists for the range of deep UV to visible light, Proc. SPIE, by S. Koibuchi et al, vol. 539, pp. 182 (1985), and "a polyvinyl phenol resin/azide compound" resist in Azide-phenolic resin resists sensitive to visible light, Proc. SPIE, by S. Nonogaki et al, vol. 539, pp. 189 (1985).
Such negative type photoresist fundamentally consisting of an alkali soluble resin and an azide compound can be dissolved in an alkaline aqueous solution with no swelling of the alkali soluble resin, and the azide compound generates nitrene (-N:) by light irradiation to act as a photo crosslinking agent or a photo addition agent.
A chemical sensitization series resist composition containing a photo acid generating agent is described in U.S. Pat. Nos. 410,201 and 873,914. The chemical sensitization series resist composition is a pattern forming material in which acid is generated in an exposed portion by irradiation of radial rays such as far ultraviolet rays, and the solubilities of an irradiated portion and a non-irradiated portion to a developing solution are changed by the reaction in which this acid is used as a catalyst to form a pattern on a substrate.
A positive type chemical sensitization series resist can be roughly classified as (1) a three components system comprising an alkali soluble resin, a compound, generating acid (a photo acid generating agent) by exposure to radial rays, and an anti-dissolution compound, and (2) a two component system comprising a resin having a group which becomes alkali soluble by a reaction with acid and a photo acid generating agent.
A negative type chemical sensitization series resist can be roughly classified as (1) a three components system comprising an alkali soluble resin, a compound, generating acid (a photo acid generating agent) by exposure to radial rays, and an acid crosslinking agent, and (2) a two component system comprising a resin having a group which becomes alkali insoluble by a reaction with acid and a photo acid generating agent.
Also, the example of "a phenol resin series acid catalyst crosslinking type negative type resist" is described in Acid-Catalyzed Cross-Linking in Phenolic-Resin-Based Negative Resists, by A. K. Berry et al (ACS Publication, No. 412, pp. 86 to 99) as the most typical composition.
In general, a photoresist in which an alkali soluble resin is contained as a primary component has a markedly excellent resolution compared with the other rubber series negative type resist, and is utilized for high resolution as an etching protective layer in preparing an integrated circuit such as IC, LSI and a gate electrode of a liquid crystal display.
In recent years, a substrate processing technique in which a dry etching method is used in keeping with a fineness due to a high integration of a integrated circuit has been used. In the art, however, fine processings of several .mu.m are carried out by a wet etching method having merit in terms of equipment price and throughput. Further, there has come to be carried out a substrate processing technique in which a dry etching method and a wet etching method are combined in order to prevent electrostatic destruction of the element. In fine processing by such a wet etching method, adhesiveness of a resist layer to the substrate is very important in addition to the resolution. That is, resist patterns of about 1 to 3 .mu.m in a substrate processed only by a wet etching method and about 0.5 to 1 .mu.m in a substrate processed by a dry etching method and a wet etching method are requested so as to strongly adhere the resist pattern on a substrate without peeling off from the substrate through development and wet etching. A conventional photoresist is not generally satisfactory in adhesiveness and an improvement thereof is desired.